1. Field of The Invention
This invention relates to a method for fabricating a ceramic composite body having a laminar structure and at least one hollow portion therein.
2. Description of the Prior Art
FIG. 10 shows a ceramic composite body 9 having a hollow portion 911 therein. For the fabrication of such a hollow ceramic composite body, it is usual to provide ceramic sheets 92, 93 obtained from a ceramic powder and a binder, and an opening-bearing ceramic sheet 91 having an opening 911.
Subsequently, the ceramic sheet 91 is sandwiched between the sheets 92 and 93, and pressed at a compression pressure of 5 MPa to 25 MPa under heating conditions of 70.degree. C. to 160.degree. C. By this, the ceramic sheets 91 to 93 are bonded together to provide a green ceramic body 9.
The green body 9 is sintered to obtain a ceramic composite body having a hollow portion therein as set out in Japanese laid-open Patent Application No. 2-50494.
The binder component or components contained in the ceramic sheets 91 to 93 are softened by the heating. In this condition, the ceramic sheets 91 to 93 are pressed whereupon the respective sheets 91 to 93 are strongly bonded together through the binder component serving as a bonding agent. When the thus obtained green body is sintered, the resultant ceramic composite body 9 is obtained as having little interstices therebetween.
However, the method has the following problem. As stated, the individual ceramic sheets 91 to 93 are softened upon heating, under which a high compression pressure is applied to the sheets. This may undesirably cause great deformation of the ceramic sheets 92, 93 at portions corresponding to the opening 911 of the sheet 91. In the case, the hollow portion 911 may be at least partly closed or deformed. Thus, an undesirably deformed ceramic composite body 9 will be fabricated.
In order to avoid this problem, Japanese Laid-open Patent Application No. 59-29107 proposes the fabrication method which follows.
As shown in FIG. 11, ceramic sheets 91 to 93 are, respectively, provided. Separately, a bonding slurry 98 is provided as having the same composition as that of the ceramic sheets 91 to 93.
The bonding slurry 98 is applied to opposite sides of the ceramic plate 91. Thereafter, the thus applied ceramic plate 91 is sandwiched between the ceramic sheets 92, 93, followed by pressing at a low compression pressure, for example, of about 1 MPa at a low temperature of 30.degree. C. to 50.degree. C.
By this, the ceramic sheets 91 to 93 are bonded together to provide a green composite body 99. The composite body 99 is then sintered to obtain a ceramic composite body having a hollow portion therein.
According to this method, the ceramic sheets 91 to 93 can be laminated at low temperature and low pressure. Accordingly, the ceramic sheets 91 to 93 do not suffer softening or deformation during the course of the pressing.
Nevertheless, the method is disadvantageous in that the ceramic sheet 91 has to be coated with the bonding slurry 98 and dried, so that the fabrication procedure becomes complicated, thus inviting a rise in cost.
Additionally, the coating and drying steps require proper control in viscosity of the slurry 98, the coating thickness, and the drying conditions of the slurry 98 under which the slurry 98 keeps good adhesiveness.